1. Field of the Invention
The present invention relates to an improvement in a semiconductor laser.
More particularly, the present invention concerns an improved structure of the semiconductor laser mount for obtaining accurate position and direction of the laser with respect to the mount.
2. Prior Art
As is well known, semiconductor lasers require a good heat radiation and dissipation, since a current of a high density flows in it when oscillating. Accordingly, in order to assure the good heat dissipation, the semiconductor laser chip is usually mounted on a copper heat sink or mount. As shown in FIG. 1, it has been known that a sub-mount 2 of copper or silicon is inserted between the semiconductor laser chip 4 and a main mount 1 of copper. Solder layers 3 and 31 are used for bonding the semiconductor laser chip 4 on the sub-mount 2 and the sub-mount 2 on the main mount 1, respectively.
In the semiconductor laser device, such sub-mount 2 is usually shaped in a rectangular parallelopiped, since such shape is suitable for making with an accurate size and shape. The accuracy of the shape of the sub-mount is advantageous in good bonding necesary for good heat dissipation and in accurate positioning necessary for avoiding undesirable masking of oscillated light. The bonding of the laser chip on the sub-mount is advantageous in that the testing of the semiconductor laser chip 4 can be made for the chip bonded on the sub-mount 2.
The sub-mount 2 with the semiconductor laser chip 4 thereon is then bonded on the copper heat sink or main mount 1, and the bonding requires a high accuracy in position and direction. Since no particular means is devised for attaining a high accuracy of the position and direction in the conventional structure of FIG. 1, it has been very difficult to attain a high accuracy of position and direction in bonding between the sub-mount and the main mount.
In summary, the conventional configuration of FIG. 1 has not fulfilled the requirements of bonding of the sub-mount 2 with semiconductor laser chip 4 thereon with very highly accurate positional and directional relation with ease and high manufacturing yield.